(function (window, undefined) {
    class Ball extends Father {
        constructor(parent, option = { width: 20, height: 20, color: "skyblue" }) {
            super(parent, option)
        }
        renderBall () {
            this.balls = []
            super.render(this.balls)
            this.balls[0].style.borderRadius = "50%"
            this.balls[0].style.position = "absolute"
            this.balls[0].style.zIndex = "888"
            
            this.balls[0].style.left = document.documentElement.offsetWidth / 2 + "px"
            this.balls[0].style.bottom = document.documentElement.offsetWidth / 2 - document.documentElement.offsetWidth * 0.45 + this.balls[0].offsetHeight + "px"
            // console.log(this.balls[0].style.bottom);

        }
    }
    window.Ball = Ball
})(window, undefined)